The need to monitor and measure gas and liquid pressures has led to the development of a variety of pressure transducing methods. The monitoring and measuring of pressures at remote or inaccessible sites is usually accomplished by one of the two following methods:
(1) The pressure is transmitted through a pipe or tube to a centrally placed transducer or gauge, or
(2) A remote transducer probe is employed which sends a converted signal to a central recording instrument.
The use of the first method requires a fluid connection to the pressure medium being measured. This is not desirable when the fluid column can cause the escape of noxious chemicals, be an avenue for infectious agents, or be a site for obstruction by objects, blood clots, or other protein materials.
The use of the second method which employs a remote transducer probe is also not without disadvantages. The most commonly used remote transducer probes are usually mechanical to electrical transducers which convert the movement of a surface or diaphragm into an electrical signal. Such transducers when reduced to the sizes of 5 mm. or less exhibit too much baseline drift and temperature instability to make accurate measurements at small pressure changes (1 mm Hg) over long periods of time, such as weeks.
There is a special need for a simple, inexpensive, compact, and accurate apparatus which is suitable for monitoring pressures within the body of living animals for clinical and medical research purposes; e.g., the measuring of intracranial pressure.